The liquid phase epoxidation of propene with hydrogen peroxide in the presence of a titanium silicalite catalyst is known from EP 0 100 119 A1. The reaction is usually carried out with a fixed bed catalyst at a pressure of more than 10 bar to achieve high propene concentrations in the liquid phase reaction mixture. The epoxidation is highly exothermal and requires adequate temperature control, because excessive reaction temperatures lead to increased by-product formation which reduces product selectivity for propene oxide.
EP 0 659 473 A1 describes an epoxidation of propene with a titanium silicalite catalyst using a reactor having several adiabatic fixed beds, where liquid reaction mixture is withdrawn after each fixed bed, cooled in an external cooler and is partially returned to the entry of the respective fixed bed.
EP 1 247 806 A1 describes epoxidation of propene with a titanium silicalite catalyst in a cooled fixed bed reactor using a cooling medium having a minimum temperature of 40° C. and limiting the maximum temperature of the catalyst fixed bed to 60° C. Tubular or multi-tubular reactors having a cooling jacket are used for this purpose.
WO 2005/068062 describes epoxidation of propene with a titanium silicalite catalyst in a tube bundle reactor which has a multitude of parallel reaction tubes cooled with a common cooling jacket. The catalyst is arranged in the tubes and cooling medium is passed through the jacket space in co-current, entering the jacket space near the entry of the tubes where starting materials are fed and exiting the jacket space near the end of the tubes. Baffles may be arranged in the jacket space to guide the flow of cooling medium transvers to the reaction tubes in order to improve the heat transfer. The jacket space may be divided into several zones and different cooling media or cooling media of different temperature can be used in the separate zones. WO 2005/068062 teaches the use of helical reaction tubes instead of straight reaction tubes to achieve a more uniform heat removal from the tubes and to avoid hot spots.